Subject: Re: Mb problem
From: Stephen & Kathy skmort@..........
Date: Thu, 31 Mar 2005 12:01:52 -0800
Thank you very much,,, works great,,, exactly what I ordered,, HA!!!
Stephen
38.828N 120.979W
John or Jan Lahr wrote:
> Stephen,
>
> I've updated the page on mb: http://jclahr.com/science/software/mb/
>
> It now includes the source and compiled code for computing magnitude via
> the Q table
> used by NEIC as well as by the formula given by Larry Braile.
>
> There is a link to the graph by Gutenberg and Richter (1956) which is
> the basis
> for the Q table.
>
> Cheers,
> John
>
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Lehmann
From: 1goss@...........
Date: Sat, 02 Apr 2005 01:21:18 +0000
I have built a Lehmann seismorraph using the 1/2 pipe and using the pipe union for a pivot point.
My question is when setting the period for the 30 inch boom.Is that from left to right then back to left if this is the case I am only getting to about 10 sec also should the boom be level. Should the gate effect take care of the swing back to center.
It has been about 4 years since I built the last one and I dont remember having so much truble setting it
thanks Bryan S Goss
I have built a Lehmann seismorraph using the 1/2 pipe and using the pipe union for a pivot point.
My question is when setting the period for the 30 inch boom.Is that from left to right then back to left if this is the case I am only getting to about 10 sec also should the boom be level. Should the gate effect take care of the swing back to center.
It has been about 4 years since I built the last one and I dont remember having so much truble setting it
thanks Bryan S Goss
Subject: Re: Lehmann
From: ChrisAtUpw@.......
Date: Fri, 1 Apr 2005 20:56:14 EST
In a message dated 02/04/2005, 1goss@........... writes:
> I have built a Lehman seismograph using the 1/2 pipe and using the pipe
> union for a pivot point.
> My question is when setting the period for the 30 inch boom. Is that from
> left to right then back to left if this is the case I am only getting to about
> 10 sec also should the boom be level? Should the gate effect take care of
> the swing back to centre.
Hi Bryan,
The period is for a complete oscillation, say from when it is central,
to one extreme, to the other extreme and then back again to the centre. The
base levelling screws should be set up so that the pendulum comes back to the
central position.
The boom itself does not have to be level. It is the small angle
between the true vertical and the line joining the top and bottom pivot points
which is critical.
You can make a good bottom pivot using a ball bearing. See Frank
Cooper and John Cole http://pages.prodigy.net/fxc/ and
http://pages.prodigy.net/fxc/JC.html
It is quite easy to make a magnetic damper with 4 NdFeB magnets and an
Al or Cu plate.
Regards,
Chris Chapman
In a message dated 02/04/2005, 1gos=
s@........... writes:
I have built a Lehman seismogra=
ph using the 1/2 pipe and using the pipe union for a pivot point.
My question is when setting the period for the 30 inch boom. Is that from l=
eft to right then back to left if this is the case I am only getting to abou=
t 10 sec also should the boom be level? Should the gate effect take care of=20=
the swing back to centre.
Hi Bryan,
The period is for a complete oscillatio=
n, say from when it is central, to one extreme, to the other extreme and the=
n back again to the centre. The base levelling screws should be set up so th=
at the pendulum comes back to the central position.
The boom itself does not have to be lev=
el. It is the small angle between the true vertical and the line joining the=
top and bottom pivot points which is critical.
You can make a good bottom pivot using=20=
a ball bearing. See Frank Cooper and John Cole http://pages.prodigy.net/fxc/ and http://pages.prodigy.net/fxc/JC.html
It is quite easy to make a magnetic dam=
per with 4 NdFeB magnets and an Al or Cu plate.
Regards,
Chris Chapman
Subject: Re: Lehmann
From: 1goss@...........
Date: Sat, 02 Apr 2005 02:16:13 +0000
Thanks for the reply Chris I will post pictures when I get it all going.
Bryan S Goss
In a message dated 02/04/2005, 1goss@........... writes:
> I have built a Lehman seismograph using the 1/2 pipe and using the pipe
> union for a pivot point.
> My question is when setting the period for the 30 inch boom. Is that from
> left to right then back to left if this is the case I am only getting to about
> 10 sec also should the boom be level? Should the gate effect take care of
> the swing back to centre.
Hi Bryan,
The period is for a complete oscillation, say from when it is central,
to one extreme, to the other extreme and then back again to the centre. The
base levelling screws should be set up so that the pendulum comes back to the
central position.
The boom itself does not have to be level. It is the small angle
between the true vertical and the line joining the top and bottom pivot points
which is critical.
You can make a good bottom pivot using a ball bearing. See Frank
Cooper and John Cole http://pages.prodigy.net/fxc/ and
http://pages.prodigy.net/fxc/JC.html
It is quite easy to make a magnetic damper with 4 NdFeB magnets and an
Al or Cu plate.
Regards,
Chris Chapman
In a message dated 02/04/2005, 1gos=
s@........... writes:
I have built a Lehman seismogra=
ph using the 1/2 pipe and using the pipe union for a pivot point.
My question is when setting the period for the 30 inch boom. Is that from l=
eft to right then back to left if this is the case I am only getting to abou=
t 10 sec also should the boom be level? Should the gate effect take care of=20=
the swing back to centre.
Hi Bryan,
The period is for a complete oscillatio=
n, say from when it is central, to one extreme, to the other extreme and the=
n back again to the centre. The base levelling screws should be set up so th=
at the pendulum comes back to the central position.
The boom itself does not have to be lev=
el. It is the small angle between the true vertical and the line joining the=
top and bottom pivot points which is critical.
You can make a good bottom pivot using=20=
a ball bearing. See Frank Cooper and John Cole http://pages.prodigy.net/fxc/ and http://pages.prodigy.net/fxc/JC.html
It is quite easy to make a magnetic dam=
per with 4 NdFeB magnets and an Al or Cu plate.
Regards,
Chris Chapman
Subject: Re: Lehmann
From: John or Jan Lahr JohnJan@........
Date: Fri, 01 Apr 2005 20:04:39 -0700
Hi Bryan,
The period is measured over one complete swing, from left to right and back
again. It's not easy
to get a period greater than about 15 seconds. If the connection between
the mast and the base
has the least amount of flex, then the mast will bend very slightly toward
the boom. The symptom
of this is that the boom will tend to swing to one side or the other rather
than finding a stable
center position when the period is adjusted to be very long.
Cheers,
John
At 06:21 PM 4/1/2005, you wrote:
>I have built a Lehmann seismorraph using the 1/2 pipe and using the pipe
>union for a pivot point.
>My question is when setting the period for the 30 inch boom.Is that from
>left to right then back to left if this is the case I am only getting to
>about 10 sec also should the boom be level. Should the gate effect take
>care of the swing back to center.
>
>It has been about 4 years since I built the last one and I dont remember
>having so much truble setting it
>thanks Bryan S Goss
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Got it going I think
From: 1goss@...........
Date: Sat, 02 Apr 2005 22:11:28 +0000
I got my Lehman Seismometer up and running I think I may have my gain set a bit high, But I think it is ok. let me know if it looks ok, I am just waiting on an event.
My setup is a remote computer in my shop about 200ft away. linked to high speed internet via 2.4 gig network connection. From there to my comcast cable then to you
I purchased Larrys 16-Bit Serial Output A/D Board for WinSDR with GPS and it is working great.
Thanks for the help on setting the boom period I got it to about 12 sec.
THE LINK https://home.comcast.net/~bryangoss/ch1.gif
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Public Seismic Network Mailing List (PSN-L)
Subject: Re: Got it going I think
From: ChrisAtUpw@.......
Date: Sat, 2 Apr 2005 19:37:10 EST
In a message dated 02/04/2005, 1goss@........... writes:
> I got my Lehman Seismometer up and running I think I may have my gain set a
> bit high, But I think it is ok.
HI Bryan,
It looks like you have a fairly high gain on the amplifier. I suggest
that you examine sections of the trace, do a FFT on it and check to see if the
~six second ocean background is dominant or if there is a lot of other noise.
Try wedging the mass so that it can't move to check on instrument noise? I
can't tell much from the drumplot, since I don't know how it was scaled. It
doesn't show any waveforms or any peak counts. You need to click on X-Scale at the
top of the display and then select 'counts'.
The display shows small deflections during the night, but much larger
ones during the 'working day'. Do you have a lot of traffic / industrial
noise?
What sort of suspensions / bearings are you using? A 12 sec plot
doesn't give you much 'headroom' over the 6 sec microseisms.
Regards,
Chris Chapman
In a message dated 02/04/2005, 1gos=
s@........... writes:
I got my Lehman Seismometer up=20=
and running I think I may have my gain set a bit high, But I think it is ok.=
HI Bryan,
It looks like you have a fairly high ga=
in on the amplifier. I suggest that you examine sections of the trace, do a=20=
FFT on it and check to see if the ~six second ocean background is dominant o=
r if there is a lot of other noise. Try wedging the mass so that it can't mo=
ve to check on instrument noise? I can't tell much from the drumplot, since=20=
I don't know how it was scaled. It doesn't show any waveforms or any peak co=
unts. You need to click on X-Scale at the top of the display and then select=
'counts'.
The display shows small deflections dur=
ing the night, but much larger ones during the 'working day'. Do you have a=20=
lot of traffic / industrial noise?
What sort of suspensions / bearings are=
you using? A 12 sec plot doesn't give you much 'headroom' over the 6 sec mi=
croseisms.
Regards,
Chris Chapman
Subject: Re: Got it going I think
From: BOB BARNS royb1@...........
Date: Sat, 02 Apr 2005 20:46:56 -0500
Hi,
My suggestion for setting the gain is to set it for just a few counts
from the A/D on a very quiet day.
Bob Barns
ChrisAtUpw@....... wrote:
> In a message dated 02/04/2005, 1goss@........... writes:
>
>> I got my Lehman Seismometer up and running I think I may have my gain
>> set a bit high, But I think it is ok.
>
>
>
> HI Bryan,
>
> It looks like you have a fairly high gain on the amplifier. I
> suggest that you examine sections of the trace, do a FFT on it and check
> to see if the ~six second ocean background is dominant or if there is a
> lot of other noise. Try wedging the mass so that it can't move to check
> on instrument noise? I can't tell much from the drumplot, since I don't
> know how it was scaled. It doesn't show any waveforms or any peak
> counts. You need to click on X-Scale at the top of the display and then
> select 'counts'.
> The display shows small deflections during the night, but much
> larger ones during the 'working day'. Do you have a lot of traffic /
> industrial noise?
>
> What sort of suspensions / bearings are you using? A 12 sec plot
> doesn't give you much 'headroom' over the 6 sec microseisms.
>
> Regards,
>
> Chris Chapman
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: pictures help
From: 1goss@...........
Date: Sun, 03 Apr 2005 03:57:29 +0000
This is a screenshot of WinSDR It shows the 6 sec microseisms I think?
https://home.comcast.net/~bryangoss/winsdr.jpg
This is the boom pivot point a pipe union and razor blade
https://home.comcast.net/~bryangoss/pipeunion.jpg
This is the damping
https://home.comcast.net/~bryangoss/damping.jpg
The bolt and 25mm wire
https://home.comcast.net/~bryangoss/boltwire.jpg
The 5lb weight and coil
https://home.comcast.net/~bryangoss/coil.jpg
The overall I put the Seismograph in a clear box to prevent draft bit I need to seal off the bottom this picture shows entire system and my messy shop!!!!!
https://home.comcast.net/~bryangoss/overall.jpg
https://home.comcast.net/~bryangoss/setup.jpg
Chris I am not sure how to do the FFT. I hope the screenshot of winsdr will help, Thanks for the help If you all see somthing to improve I will try to do it. is the ball bearing better than the razer blade?
Thanks Very Much Bryan S Goss Corinth MS
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: boom pivot
From: Angel sismos@..............
Date: Sun, 3 Apr 2005 04:52:16 -0500
Bryan,
Congratulations and thanks for all the pictures, they help.
I really think that you can with very little more work you can greatly
improve the pivot. There are several ways to make the pivot better,
the ball bearing is a good and easy way. I have used wire pivot which
is harder make especially after the fact, here are some pictures.
www.volcanbaru.com/gardengate
The Winquake software you are using will allow you to do an FFT.
regards,
Angel
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: boom pivot
From: Dave Nelson davenn@...............
Date: Sun, 03 Apr 2005 20:06:35 +1000
>www.volcanbaru.com/gardengate
>The Winquake software you are using will allow you to do an FFT.
>regards,
>Angel
good pics Angel,
the last pic is missing though, maybe u
forgot to load that one up to ur www site :)
I see u are using a similar principle to the wire pivot used in the long
period seismometer by the Worldwide Standard Seismic Network
I used one of those seismo's back in New Zealand and it was VERY
successful.
One of the Denver area PSN'ers also has one think that was John Lahr :)
cheers
Dave N
Sydney
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: pictures help
From: Dave Nelson davenn@...............
Date: Sun, 03 Apr 2005 20:11:24 +1000
Excellent work Bryan,
great to see another amateur station getting up and running
on behalf of the PSN I would like to invite you to submit your station
information to me so I can include you on the PSN station map
visit my pages at http://www.sydneystormcity.com/map.htm
and below the world map you sill see a list of the info I collect for the
station info
.... there you will also see that click on sections of the map or dots and
find out about the other PSN stations around the world
cheers
Dave N
Sydney
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: the warning of earthquakes
From: Alexandr Yagodin midia@..............
Date: Sun, 03 Apr 2005 14:21:06 +0200
I welcome all from Haifa!
I do the warning of earthquakes in Israel and near areas on distance up to 1000 - 1500 kms.
For this purpose I use behaviour of animals. I have learned to test for this purpose dogs.
Time of an advancing of a beginning of earthquake - not less than 20 - 40 minutes.
If someone wants to participate in the warning of earthquakes - I can help with testing dogs.
Yours faithfully.
Alexandr Yagodin
midia@..............
I welcome all from Haifa
!
I do the warning of earthquakes in Israel and near areas on distance up to
1000 - 1500 kms.
For this purpose I use behaviour of animals. I have learned to test for this
purpose dogs.
Time of an advancing of a beginning of earthquake - not less than 20 - 40
minutes.
If someone wants to participate in the warning of earthquakes - I can help
with testing dogs.
Yours faithfully.
Alexandr Yagodin
midia@..............
Subject: Re: the warning of earthquakes
From: Mark Robinson mark.robinson@...............
Date: Mon, 04 Apr 2005 00:46:03 +1200
Hi folks,
Speaking of warning of earthquakes, I made an offhand prediction that
there was going to be a significant earthquake six hours or so before
the 8.7 in Indonesia.
This was based this on unusual long period activity on the USGS
instrument in Wellington which I have associated with the run up to
large quakes in the past. Strange patterns of waves of similar period to
the global ringing which happens after a large quake.
Perhaps some of the learned people here could tell me if this is a known
phenomenon and if so point me at some reading material.
Welcome to here Alexandr, I'm not aware of anyone else here working animals.
All the best,
regards
Mark
(my tsunami warning system is happening very slowly, but I do seem to
get the ITIC warnings within 20 minutes of major events, when it's
actually working, and they ring a bell and fire my pager)
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: the warning of earthquakes
From: Alexandr Yagodin midia@..............
Date: Sun, 03 Apr 2005 16:21:17 +0200
Hi, Mark!
You can tell, what was speed of waves, which you measured before earthquake?
Successes.
Alexandr.
You can use the interpreter with Russian on English?
----- Original Message -----
From: "Mark Robinson"
To:
Sent: Sunday, April 03, 2005 2:46 PM
Subject: Re: the warning of earthquakes
> Hi folks,
>
> Speaking of warning of earthquakes, I made an offhand prediction that
> there was going to be a significant earthquake six hours or so before
> the 8.7 in Indonesia.
>
> This was based this on unusual long period activity on the USGS
> instrument in Wellington which I have associated with the run up to
> large quakes in the past. Strange patterns of waves of similar period to
> the global ringing which happens after a large quake.
>
> Perhaps some of the learned people here could tell me if this is a known
> phenomenon and if so point me at some reading material.
>
> Welcome to here Alexandr, I'm not aware of anyone else here working
animals.
>
> All the best,
>
> regards
> Mark
>
> (my tsunami warning system is happening very slowly, but I do seem to
> get the ITIC warnings within 20 minutes of major events, when it's
> actually working, and they ring a bell and fire my pager)
> __________________________________________________________
>
> Public Seismic Network Mailing List (PSN-L)
>
> To leave this list email PSN-L-REQUEST@.............. with
> the body of the message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.
>
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: noise
From: 1goss@...........
Date: Sun, 03 Apr 2005 22:02:24 +0000
I am having problems with noise during the night. Oddly it starts about 9:00pm and ends about 11:00 am.
9:00pm WinSDR screenshot https://home.comcast.net/~bryangoss/noise9pm.jpg
11:00am WinSDR screenshot https://home.comcast.net/~bryangoss/noise11am.jpg
I think these pictures will explain much more than I can.
I thought it could be because the shop has a concrete floor and the air in the shop heats up to aournd 70F during the day and cools to around 36F at night. I believe the slower cooling of the floor during the night could be causing convection in the box. I tried to seal the box off and covered it with a blanket but that did not work. Could it be caused by the temperature change in the mineral oil and the vertical dampener?
I ran FFT but to be honest, I'm not sure how to read it.
Thank you for any help you can offer.
Bryan S. Goss
In a message dated 02/04/2005, 1goss@........... writes:
> I got my Lehman Seismometer up and running I think I may have my gain set a
> bit high, But I think it is ok.
HI Bryan,
It looks like you have a fairly high gain on the amplifier. I suggest
that you examine sections of the trace, do a FFT on it and check to see if the
~six second ocean background is dominant or if there is a lot of other noise.
Try wedging the mass so that it can't move to check on instrument noise? I
can't tell much from the drumplot, since I don't know how it was scaled. It
doesn't show any waveforms or any peak counts. You need to click on X-Scale at the
top of the display and then select 'counts'.
The display shows small deflections during the night, but much larger
ones during the 'working day'. Do you have a lot of traffic / industrial
noise?
What sort of suspensions / bearings are you using? A 12 sec plot
doesn't give you much 'headroom' over the 6 sec microseisms.
Regards,
Chris Chapman
In a message dated 02/04/2005, 1gos=
s@........... writes:
I got my Lehman Seismometer up=20=
and running I think I may have my gain set a bit high, But I think it is ok.=
HI Bryan,
It looks like you have a fairly high ga=
in on the amplifier. I suggest that you examine sections of the trace, do a=20=
FFT on it and check to see if the ~six second ocean background is dominant o=
r if there is a lot of other noise. Try wedging the mass so that it can't mo=
ve to check on instrument noise? I can't tell much from the drumplot, since=20=
I don't know how it was scaled. It doesn't show any waveforms or any peak co=
unts. You need to click on X-Scale at the top of the display and then select=
'counts'.
The display shows small deflections dur=
ing the night, but much larger ones during the 'working day'. Do you have a=20=
lot of traffic / industrial noise?
What sort of suspensions / bearings are=
you using? A 12 sec plot doesn't give you much 'headroom' over the 6 sec mi=
croseisms.
Regards,
Chris Chapman
Subject: Re[2]: noise
From: Angel sismos@..............
Date: Sun, 3 Apr 2005 17:38:50 -0500
Bryan,
Post a picture of the FFT.
Do you have forced air central heating?
regards,
Angel
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: RE: noise
From: Bob Hancock Bob.Hancock@............
Date: Sun, 03 Apr 2005 15:50:22 -0700
Bryan -
Not sure where you are located, but the microseisms are high right now. You
can check out a Navy web site that shows ocean wave height around the world,
from current, to projected wave height for 144 hours in the future. Ocean
waves are a big contributor to seismic noise in the 6 to 10 second period
noise. The link to web site is
https://www.fnmoc.navy.mil/PUBLIC/WAM/all_glbl.html
More information can be found with the ALBUQUERQUE SEISMOLOGICAL LABORATORY
(ASL) publication, OBSERVATIONS AND MODELING OF SEISMIC BACKGROUND NOISE.
This can be downloaded from the following link
http://aslwww.cr.usgs.gov/Publications/pdffiles/asl93-~1.pdf
Another quick reference for microseisms is the Lamont-Daugherty Cooperative
Seismic Network (LCSN), near New York City. Their link is
http://www.ldeo.columbia.edu/cgi-bin/LCSN/WebSeis/24hr_heli.pl
Hopefully these links will help you in making determinations of your seismic
activity. As you can see the microseisms are high on the LCSN web site, and
I am experiencing high microseisms at my location, about 30 miles west of
Tucson, Arizona.
Bob Hancock
Tucson, AZ
-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@............... On
Behalf Of 1goss@...........
Sent: Sunday, April 03, 2005 15:02
To: psn-l@..............
Subject: Re: noise
I am having problems with noise during the night. Oddly it starts about
9:00pm and ends about 11:00 am.
9:00pm WinSDR screenshot https://home.comcast.net/~bryangoss/noise9pm.jpg
11:00am WinSDR screenshot https://home.comcast.net/~bryangoss/noise11am.jpg
I think these pictures will explain much more than I can.
I thought it could be because the shop has a concrete floor and the air in
the shop heats up to aournd 70F during the day and cools to around 36F at
night. I believe the slower cooling of the floor during the night could be
causing convection in the box. I tried to seal the box off and covered it
with a blanket but that did not work. Could it be caused by the temperature
change in the mineral oil and the vertical dampener?
I ran FFT but to be honest, I'm not sure how to read it.
Thank you for any help you can offer.
Bryan S. Goss
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Noise FFT picture
From: 1goss@...........
Date: Sun, 03 Apr 2005 23:38:51 +0000
As requested by Angel:
"Post a picture of the FFT.
Do you have forced air central heating?
regards,
Angel"
No I don't have any heating in the shop it is a 20 x 40 about 100 ft from my house.
Here is a 10 minute clip at peak noise with WinQuake.
https://home.comcast.net/~bryangoss/peak.jpg
Here is the same clip FFT. I put a v where the curser was.
https://home.comcast.net/~bryangoss/FFT.jpg
Also Thank you all for helping the links you sent will help Bob.
and as Chris sugested I may change my pivot point to a ball bering.
> Bryan,
>
> Post a picture of the FFT.
>
> Do you have forced air central heating?
>
> regards,
>
> Angel
>
> __________________________________________________________
>
> Public Seismic Network Mailing List (PSN-L)
>
> To leave this list email PSN-L-REQUEST@.............. with
> the body of the message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.
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Public Seismic Network Mailing List (PSN-L)
Subject: Re: noise
From: ChrisAtUpw@.......
Date: Sun, 3 Apr 2005 20:14:06 EDT
In a message dated 03/04/2005, 1goss@........... writes:
> I am having problems with noise during the night. Oddly it starts about
> 9:00pm and ends about 11:00 am.
>
> 9:00pm WinSDR screenshot https://home.comcast.net/~bryangoss/noise9pm.jpg
Hi Bryan,
This is NOT ocean background! The background is about 10 cycles per
minute, so 10 mins should give ~100 peaks.
> 11:00am WinSDR screenshot
> https://home.comcast.net/~bryangoss/noise11am.jpg
This could well be the ocean background.
> I thought it could be because the shop has a concrete floor and the air in
> the shop heats up to around 70F during the day and cools to around 36F at
> night. I believe the slower cooling of the floor during the night could be
> causing convection in the box. I tried to seal the box off and covered it with a
> blanket but that did not work. Could it be caused by the temperature change in
> the mineral oil and the vertical dampener?
Ouch! Gee! You need to keep the temperature a lot more constant. Seal the
joints of the perspex case with the special 2" clear tape that you use to
make glass joins in greenhouse windows. Then get a large cardboard box, seal the
top joins with 2" gaffer tape and place it over the perspex box. Get a 15 W
light bulb and place it inside the top of the perspex box. This heating should
keep a stable temperature gradient inside, but you should really think long
term of finding somewhere which only changes temperature by a few degrees from
day to night. If the cardboard box and the bulb give a significant improvement,
think in terms of making a 2" thick cellotex case - see the bottom photo at
http://pages.prodigy.net/fxc/
It can't be a direct effect of changes in oil viscosity, since the
damping is greatest when the temperature is least and you see the opposite. I
suspect that you may be correct in assuming that you have turbulent air cooling
during the night.
> I ran FFT but to be honest, I'm not sure how to read it.
The vertical axis is the logarithmic signal amplitude. The horizontal
axis is the logarithmic frequency, with higher frequencies toward the right.
It will be 100, 10, 1, 0.1, 0.01, 0.001 Hz. There is a cursor on the screen
which reads out in frequency and period figures at the top of the screen. Your
plot shows excessive low frequency signals, which could well be associated with
cooling.
Regards,
Chris Chapman
In a message dated 03/04/2005, 1gos=
s@........... writes:
I am having problems with noise=
during the night. Oddly it starts about 9:00pm and ends about 11:00 am.
9:00pm WinSDR screenshot https://home.comcast.net/~bryangoss/noise9pm.jpg
Hi Bryan,
This is NOT ocean background! The backg=
round is about 10 cycles per minute, so 10 mins should give ~100 peaks. =
;
11:00am WinSDR screenshot =
https://home.=
comcast.net/~bryangoss/noise11am.jpg
This could well be the ocean background=
..
I thought it could be because t=
he shop has a concrete floor and the air in the shop heats up to around 70F=20=
during the day and cools to around 36F at night. I believe the slower coolin=
g of the floor during the night could be causing convection in the box. I tr=
ied to seal the box off and covered it with a blanket but that did not work.=
Could it be caused by the temperature change in the mineral oil and the ver=
tical dampener?
Ouch! Gee! You need to keep the temperature a lot more constant. Seal the joints of the perspex case with the special 2=
" clear tape that you use to make glass joins in greenhouse windows. Then ge=
t a large cardboard box, seal the top joins with 2" gaffer tape and place it=
over the perspex box. Get a 15 W light bulb and place it inside the t=
op of the perspex box. This heating should keep a stable temperature=
gradient inside, but you should really think long term of finding somewhere=
which only changes temperature by a few degrees from day to night. If the c=
ardboard box and the bulb give a significant improvement, think in terms of=20=
making a 2" thick cellotex case - see the bottom photo at http://pages.prodigy.net/fxc/
It can't be a direct effect of changes in oil viscosity,=20=
since the damping is greatest when the temperature is least and you see the=20=
opposite. I suspect that you may be correct in assuming that you have turbul=
ent air cooling during the night.
I ran FFT but to be honest, I'm=
not sure how to read it.
The vertical axis is the logarithmic si=
gnal amplitude. The horizontal axis is the logarithmic frequency, with highe=
r frequencies toward the right. It will be 100, 10, 1, 0.1, 0.01, 0.001 Hz.=20=
There is a cursor on the screen which reads out in frequency and period figu=
res at the top of the screen. Your plot shows excessive low frequency signal=
s, which could well be associated with cooling.
Regards,
Chris Chapman
Subject: Re: pictures help
From: ChrisAtUpw@.......
Date: Sun, 3 Apr 2005 23:25:05 EDT
In a message dated 03/04/2005, 1goss@........... writes:
> This is a screenshot of WinSDR It shows the 6 sec microseisms I think?
> https://home.comcast.net/~bryangoss/winsdr.jpg
Hi Bryan,
The time scale given is four minutes. With a microseism period of ~6
sec, you should be looking at ~40 cycles total. This could fit the faster
vibrations or it could all be mostly noise. There is certainly a lot of longer
period stuff in with it.
> This is the boom pivot point a pipe union and razor blade
> https://home.comcast.net/~bryangoss/pipeunion.jpg is the ball bearing
> better than the razer blade?
Razor blades do not tend to last very long. The idea seems to have
arisen from the old system of knife edge bearings for lab balances. These used 60
deg triangular agate bars resting on a flat agate plate. This only allowed
about 200 gm load and the edge of the triangle had a tiny radius lapped onto it.
A razor blade is about 15 deg and very sharp, so the edge load is huge and
you are asking it to take > 2 kgm. Umm. Stainless ball bearings last for ~ever.
You should be able to get >20 sec response without any problems
You can buy stainless steel ball bearings ~3/16", which do not
corrode. For a flat, you can use a tungsten carbide tool insert bit for a lathe. You
can get flat triangular bits with about 0.3" sides, quite cheaply. If you
epoxy the bearing into a V hole made with centre drill on the vertical support,
turn the end of the boom rod flat and epoxy the tool bit onto this end, it
should work very well. If you mount the ball in the end of the swing arm, you will
have to do a major levelling operation every time you dismount the arm.....
> This is the damping
> https://home.comcast.net/~bryangoss/damping.jpg
You shouldn't need oil AND magnetic damping! The magnet set-up you
have should give both vertical and horizontal damping! I suggest that you remove
the oil and then reduce the magnet separation till you get just sub-critical
damping? If you can't get enough damping, use a 1/8" thick Cu plate. If you
slowly deflect the arm 1/2" to one side and then release it, it should just go
through zero by 1/16" or less and then fall back to zero.
There are several problems with oil damping. It is very temperature
sensitive, relatively difficult to set up, it is messy due to oil creep and it
collects bugs - giving 'bug-quakes'! It is also 'non linear' in that it
selectively damps short period motion much more than long period motion. The
professionals stopped using it over 50 years ago....
I use a quad NdFeB bar magnet damping set-up. Two 1/4" thick mild
steel plates 3.5" long by 2" wide are held apart by four 1/4" mild steel bolts and
additional nuts at each corner. A NS pair of rectangular NdFeB magnets, 1" x
1/2" x 1/4" are placed on the centre of the face of one plate with the long
axis parallel to the 2". A pair of SN magnets are placed on the opposing face of
the other plate and the separation is adjusted to about 1/8" to 3/16". The
central field gradient is simply huge. A 1/16" or 1/8" thick plate of soft Al or
Cu about 2" wide and 3" long is mounted on the arm. It is important to make
the damping plate wider than the 1" of the magnets to avoid field edge effects.
The main damping is over the central 1" NS magnet joint. If you mount a L
shaped Cu blade horizontally, you can just slide the magnet array further over it
to increase the damping. You also reduce the damping by increasing the
central magnetic gap. The stray field is low with this design. I put gaffer tape on
the magnet faces and then peel it off before I assemble the two plates, to
remove any magnetic debris / whiskers. You always get some and it is very
difficult to see...
> The bolt and 25mm wire
> https://home.comcast.net/~bryangoss/boltwire.jpg
>
> The 5lb weight and coil
> https://home.comcast.net/~bryangoss/coil.jpg
If you mount the sensor magnet on the arm, it will respond to changing
magnetic fields, the earth's field, power line surges, fridge motors, even to
passing cars and lorries. If you mount the coil on the arm, it will be ~free
of these interfering signals. You may detect movements of a few millionth's of
an inch!
The effective length of the arm is a bit shorter than the distance
between the centre of the mass and the knife edge. You want this to be ~30 to 40"
to give a long period. You might mount the mass quite a bit further along the
arm?
It is usual to attach the top suspension wire to a ~3" high vertical
extension plate above the screw arm. This gives a small vertical pendulum
effect and prevents the arm from rotating when it senses movement. This is
necessary if you use a ball or wire suspension.
> The overall I put the Seismograph in a clear box to prevent draft bit I
> need to seal off the bottom this picture shows entire system and my messy
> shop!!!!!
>
> https://home.comcast.net/~bryangoss/overall.jpg
This looks OK, but you probably need to seal the edges of the case.
You can buy 3" wide clear sticky tape for sealing greenhouse windows. This will
take sunlight and it does not loose adhesion with time. Don't use cellotape,
or ordinary pvc tape - they won't last long and you only want to do the job
once!
I would use two longitudinal L angles to support the whole base
suspension, the sensor and the damping array plates. I use a single bolt at the centre
of the mass end of the rig to alter the tilt angle. This makes adjustments a
whole lot easier. You can set up each section / clearance in turn and the
adjustments don't interact much.
> https://home.comcast.net/~bryangoss/setup.jpg
>
I would mount the computer and monitor further away from the seismometer.
You will certainly see a signal when you turn the monitor on, due to the large
magnetic pulse used to demagnetise the screen.
> Chris I am not sure how to do the FFT. I hope the screenshot of winsdr will
> help, Thanks for the help If you all see something to improve I will try to
> do it.
> Thanks Very Much Bryan S Goss Corinth MS
If you are using WinQuake, there is a tab labelled FFT on the top tool
bar. You place the cursor where you want to start on the trace and click on.
There should be a help file if you look for it.
Hope that this is of some help! Are there two Corinths in MS?
Regards,
Chris Chapman
In a message dated 03/04/2005, 1gos=
s@........... writes:
This is a screenshot of WinSDR=20=
It shows the 6 sec microseisms I think?
https://home.comc=
ast.net/~bryangoss/winsdr.jpg
Hi Bryan,
The time scale given is four minutes. W=
ith a microseism period of ~6 sec, you should be looking at ~40 cycles total=
.. This could fit the faster vibrations or it could all be mostly noise. Ther=
e is certainly a lot of longer period stuff in with it.
This is the boom pivot point a=20=
pipe union and razor blade
https://home.c=
omcast.net/~bryangoss/pipeunion.jpg is the ball bearing better tha=
n the razer blade?
Razor blades do not tend to last very=20=
long. The idea seems to have arisen from the old system of knife edge bearin=
gs for lab balances. These used 60 deg triangular agate bars resting on a fl=
at agate plate. This only allowed about 200 gm load and the edge of the tria=
ngle had a tiny radius lapped onto it. A razor blade is about 15 deg and ver=
y sharp, so the edge load is huge and you are asking it to take > 2 kgm.=20=
Umm. Stainless ball bearings last for ~ever. You should be able to get >2=
0 sec response without any problems
You can buy stainless steel ball bearin=
gs ~3/16", which do not corrode. For a flat, you can use a tungsten carbide=20=
tool insert bit for a lathe. You can get flat triangular bits=20=
with about 0.3" sides, quite cheaply. If you epoxy the bearing into a V hole=
made with centre drill on the vertical support, turn the end of the boom ro=
d flat and epoxy the tool bit onto this end, it should work very well. If yo=
u mount the ball in the end of the swing arm, you will have to do a major le=
velling operation every time you dismount the arm.....
This is the damping
https://home.com=
cast.net/~bryangoss/damping.jpg
You shouldn't need oil AND magnetic damping! The magnet set-up you have should give both verti=
cal and horizontal damping! I suggest that you remove the oil and th=
en reduce the magnet separation till you get just sub-critical damping? If y=
ou can't get enough damping, use a 1/8" thick Cu plate. If you slowly deflec=
t the arm 1/2" to one side and then release it, it should just go through ze=
ro by 1/16" or less and then fall back to zero.
There are several problems with oil dam=
ping. It is very temperature sensitive, relatively difficult to set up, it i=
s messy due to oil creep and it collects bugs - giving 'bug-quakes'! It is a=
lso 'non linear' in that it selectively damps short period motion much more=20=
than long period motion. The professionals stopped using it over 50 years ag=
o....
I use a quad NdFeB bar magnet damping s=
et-up. Two 1/4" thick mild steel plates 3.5" long by 2" wide are held apart=20=
by four 1/4" mild steel bolts and additional nuts at each corner. A NS pair=20=
of rectangular NdFeB magnets, 1" x 1/2" x 1/4" are placed on the centre of t=
he face of one plate with the long axis parallel to the 2". A pair of SN mag=
nets are placed on the opposing face of the other plate and the separation i=
s adjusted to about 1/8" to 3/16". The central field gradient is simply huge=
.. A 1/16" or 1/8" thick plate of soft Al or Cu about 2" wide and 3" long is=20=
mounted on the arm. It is important to make the damping plate wider than the=
1" of the magnets to avoid field edge effects. The main damping is over the=
central 1" NS magnet joint. If you mount a L shaped Cu blade horizontally,=20=
you can just slide the magnet array further over it to increase the damping.=
You also reduce the damping by increasing the central magnetic gap. The str=
ay field is low with this design. I put gaffer tape on the magnet faces and=20=
then peel it off before I assemble the two plates, to remove any magnetic de=
bris / whiskers. You always get some and it is very difficult to see...
The bolt and 25mm wire
https://home.comcast.net/~bryangoss/boltwire.jpg
The 5lb weight and coil
https://home.comcas=
t.net/~bryangoss/coil.jpg
If you mount the sensor magnet on the=20=
arm, it will respond to changing magnetic fields, the earth's field, power l=
ine surges, fridge motors, even to passing cars and lorries. If you mount th=
e coil on the arm, it will be ~free of these interfering signals. You may de=
tect movements of a few millionth's of an inch!
The effective length of the arm is a bi=
t shorter than the distance between the centre of the mass and the knife edg=
e. You want this to be ~30 to 40" to give a long period. You might mount the=
mass quite a bit further along the arm?
It is usual to attach the top suspensio=
n wire to a ~3" high vertical extension plate above the screw arm. This give=
s a small vertical pendulum effect and prevents the arm from rotating when i=
t senses movement. This is necessary if you use a ball or wire suspension.
The overall I put the Seismogr=
aph in a clear box to prevent draft bit I need to seal off the bottom this p=
icture shows entire system and my messy shop!!!!!
https://h=
ome.comcast.net/~bryangoss/overall.jpg
This looks OK, but you probably need t=
o seal the edges of the case. You can buy 3" wide clear sticky tape for seal=
ing greenhouse windows. This will take sunlight and it does not loose adhesi=
on with time. Don't use cellotape, or ordinary pvc tape - they won't last lo=
ng and you only want to do the job once!
I would use two longitudinal L angles to support the whol=
e base suspension, the sensor and the damping array plates. I use a single b=
olt at the centre of the mass end of the rig to alter the tilt angle. Thi=
s makes adjustments a whole lot easier. You can set up each section / cl=
earance in turn and the adjustments don't interact much.
https://home.comcast.net/~bryangoss/setup.=
jpg
I would mount the computer and monitor further away from the s=
eismometer. You will certainly see a signal when you turn the monitor on, du=
e to the large magnetic pulse used to demagnetise the screen.
Chris I am not sure how to do t=
he FFT. I hope the screenshot of winsdr will help, Thanks for the help If yo=
u all see something to improve I will try to do it.
Thanks Very Much Bryan S Goss Corinth MS
If you are using WinQuake, there is a t=
ab labelled FFT on the top tool bar. You place the cursor where you want to=20=
start on the trace and click on. There should be a help file if you look for=
it.
Hope that this is of some help! Are the=
re two Corinths in MS?
Regards,
Chris Chapman
Subject: Re: the warning of earthquakes
From: ChrisAtUpw@.......
Date: Sun, 3 Apr 2005 23:35:25 EDT
In a message dated 03/04/2005, mark.robinson@............... writes:
> Speaking of warning of earthquakes, I made an offhand prediction that
> there was going to be a significant earthquake six hours or so before
> the 8.7 in Indonesia.
>
> This was based this on unusual long period activity on the USGS
> instrument in Wellington which I have associated with the run up to
> large quakes in the past. Strange patterns of waves of similar period to
> the global ringing which happens after a large quake.
>
> Perhaps some of the learned people here could tell me if this is a known
> phenomenon and if so point me at some reading material.
Hi Mark,
I was certainly aware of these eigenmode signals, which are a bit
difficult to see on 'ordinary' seismometers, but I do not offhand know of any
reports. There certainly should be some about. You can also see these effects with
a really sensitive tiltmeter.
Regards,
Chris Chapman
In a message dated 03/04/2005, mark=
..robinson@............... writes:
Speaking of warning of earthqua=
kes, I made an offhand prediction that
there was going to be a significant earthquake six hours or so before
the 8.7 in Indonesia.
This was based this on unusual long period activity on the USGS
instrument in Wellington which I have associated with the run up to
large quakes in the past. Strange patterns of waves of similar period to
the global ringing which happens after a large quake.
Perhaps some of the learned people here could tell me if this is a known
phenomenon and if so point me at some reading material.
Hi Mark,
I was certainly aware of these eigenmod=
e signals, which are a bit difficult to see on 'ordinary' seismometers, but=20=
I do not offhand know of any reports. There certainly should be some about.=20=
You can also see these effects with a really sensitive tiltmeter.
Regards,
Chris Chapman
Subject: Re: the warning of earthquakes
From: Mark Robinson mark.robinson@...............
Date: Mon, 04 Apr 2005 15:49:10 +1200
ChrisAtUpw@....... wrote:
> eigenmode
Thanks Chris,
That's what I needed.
cheers
Mark
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Chris improvements
From: 1goss@...........
Date: Mon, 04 Apr 2005 08:43:58 +0000
I would like very much to see detailed pictures of your setup. It would help me to better understand the improvements you suggested.
I have 2 questions:
1. If you put the coil on the boom how do you keep the wire from interfering with the swing or period.
2 I used 3/8 all thread,as you could see. I was afraid it would bend under the weight as I noted the 4ft length of the rod was flexible when I bought it.
What size rod did you use?What size should I use? oops went over 2 questions.
3 My nightmare the only place I can put the seismograph is in my shop it is very UN-level. I could not believe how much. It sets on sand near a ditch when I level the boom their is over an inch difference from one end to the other, this makes a hard job harder. I came very close during this part of setup to "making a beer run" as we say here in the south.
I had considered pouring a small amount of concrete to try and fix this.
also tonight late I had very little noise so it seems as their was no big temperature contrast,this may well be the bigger problem. I ran FFT on the low noise output of the seismograph and I clearly saw a spike the 6 sec microseisms.
This is a good thing I right? but I am still going to improve it.
I am about 20 miles from Pickwick Lake, AL
In extreme northern MS. 50 miles north of Tupelo MS.
Thanks so much for all your help and everyone that has contributed and please forgive my bad gram-mer oveously not one of my strong points.
In a message dated 03/04/2005, 1goss@........... writes:
> This is a screenshot of WinSDR It shows the 6 sec microseisms I think?
> https://home.comcast.net/~bryangoss/winsdr.jpg
Hi Bryan,
The time scale given is four minutes. With a microseism period of ~6
sec, you should be looking at ~40 cycles total. This could fit the faster
vibrations or it could all be mostly noise. There is certainly a lot of longer
period stuff in with it.
> This is the boom pivot point a pipe union and razor blade
> https://home.comcast.net/~bryangoss/pipeunion.jpg is the ball bearing
> better than the razer blade?
Razor blades do not tend to last very long. The idea seems to have
arisen from the old system of knife edge bearings for lab balances. These used 60
deg triangular agate bars resting on a flat agate plate. This only allowed
about 200 gm load and the edge of the triangle had a tiny radius lapped onto it.
A razor blade is about 15 deg and very sharp, so the edge load is huge and
you are asking it to take > 2 kgm. Umm. Stainless ball bearings last for ~ever.
You should be able to get >20 sec response without any problems
You can buy stainless steel ball bearings ~3/16", which do not
corrode. For a flat, you can use a tungsten carbide tool insert bit for a lathe. You
can get flat triangular bits with about 0.3" sides, quite cheaply. If you
epoxy the bearing into a V hole made with centre drill on the vertical support,
turn the end of the boom rod flat and epoxy the tool bit onto this end, it
should work very well. If you mount the ball in the end of the swing arm, you will
have to do a major levelling operation every time you dismount the arm.....
> This is the damping
> https://home.comcast.net/~bryangoss/damping.jpg
You shouldn't need oil AND magnetic damping! The magnet set-up you
have should give both vertical and horizontal damping! I suggest that you remove
the oil and then reduce the magnet separation till you get just sub-critical
damping? If you can't get enough damping, use a 1/8" thick Cu plate. If you
slowly deflect the arm 1/2" to one side and then release it, it should just go
through zero by 1/16" or less and then fall back to zero.
There are several problems with oil damping. It is very temperature
sensitive, relatively difficult to set up, it is messy due to oil creep and it
collects bugs - giving 'bug-quakes'! It is also 'non linear' in that it
selectively damps short period motion much more than long period motion. The
professionals stopped using it over 50 years ago....
I use a quad NdFeB bar magnet damping set-up. Two 1/4" thick mild
steel plates 3.5" long by 2" wide are held apart by four 1/4" mild steel bolts and
additional nuts at each corner. A NS pair of rectangular NdFeB magnets, 1" x
1/2" x 1/4" are placed on the centre of the face of one plate with the long
axis parallel to the 2". A pair of SN magnets are placed on the opposing face of
the other plate and the separation is adjusted to about 1/8" to 3/16". The
central field gradient is simply huge. A 1/16" or 1/8" thick plate of soft Al or
Cu about 2" wide and 3" long is mounted on the arm. It is important to make
the damping plate wider than the 1" of the magnets to avoid field edge effects.
The main damping is over the central 1" NS magnet joint. If you mount a L
shaped Cu blade horizontally, you can just slide the magnet array further over it
to increase the damping. You also reduce the damping by increasing the
central magnetic gap. The stray field is low with this design. I put gaffer tape on
the magnet faces and then peel it off before I assemble the two plates, to
remove any magnetic debris / whiskers. You always get some and it is very
difficult to see...
> The bolt and 25mm wire
> https://home.comcast.net/~bryangoss/boltwire.jpg
>
> The 5lb weight and coil
> https://home.comcast.net/~bryangoss/coil.jpg
If you mount the sensor magnet on the arm, it will respond to changing
magnetic fields, the earth's field, power line surges, fridge motors, even to
passing cars and lorries. If you mount the coil on the arm, it will be ~free
of these interfering signals. You may detect movements of a few millionth's of
an inch!
The effective length of the arm is a bit shorter than the distance
between the centre of the mass and the knife edge. You want this to be ~30 to 40"
to give a long period. You might mount the mass quite a bit further along the
arm?
It is usual to attach the top suspension wire to a ~3" high vertical
extension plate above the screw arm. This gives a small vertical pendulum
effect and prevents the arm from rotating when it senses movement. This is
necessary if you use a ball or wire suspension.
> The overall I put the Seismograph in a clear box to prevent draft bit I
> need to seal off the bottom this picture shows entire system and my messy
> shop!!!!!
>
> https://home.comcast.net/~bryangoss/overall.jpg
This looks OK, but you probably need to seal the edges of the case.
You can buy 3" wide clear sticky tape for sealing greenhouse windows. This will
take sunlight and it does not loose adhesion with time. Don't use cellotape,
or ordinary pvc tape - they won't last long and you only want to do the job
once!
I would use two longitudinal L angles to support the whole base
suspension, the sensor and the damping array plates. I use a single bolt at the centre
of the mass end of the rig to alter the tilt angle. This makes adjustments a
whole lot easier. You can set up each section / clearance in turn and the
adjustments don't interact much.
> https://home.comcast.net/~bryangoss/setup.jpg
>
I would mount the computer and monitor further away from the seismometer.
You will certainly see a signal when you turn the monitor on, due to the large
magnetic pulse used to demagnetise the screen.
> Chris I am not sure how to do the FFT. I hope the screenshot of winsdr will
> help, Thanks for the help If you all see something to improve I will try to
> do it.
> Thanks Very Much Bryan S Goss Corinth MS
If you are using WinQuake, there is a tab labelled FFT on the top tool
bar. You place the cursor where you want to start on the trace and click on.
There should be a help file if you look for it.
Hope that this is of some help! Are there two Corinths in MS?
Regards,
Chris Chapman
In a message dated 03/04/2005, 1gos=
s@........... writes:
This is a screenshot of WinSDR=20=
It shows the 6 sec microseisms I think?
https://home.comc=
ast.net/~bryangoss/winsdr.jpg
Hi Bryan,
The time scale given is four minutes. W=
ith a microseism period of ~6 sec, you should be looking at ~40 cycles total=
.. This could fit the faster vibrations or it could all be mostly noise. Ther=
e is certainly a lot of longer period stuff in with it.
This is the boom pivot point a=20=
pipe union and razor blade
https://home.c=
omcast.net/~bryangoss/pipeunion.jpg is the ball bearing better tha=
n the razer blade?
Razor blades do not tend to last very=20=
long. The idea seems to have arisen from the old system of knife edge bearin=
gs for lab balances. These used 60 deg triangular agate bars resting on a fl=
at agate plate. This only allowed about 200 gm load and the edge of the tria=
ngle had a tiny radius lapped onto it. A razor blade is about 15 deg and ver=
y sharp, so the edge load is huge and you are asking it to take > 2 kgm.=20=
Umm. Stainless ball bearings last for ~ever. You should be able to get >2=
0 sec response without any problems
You can buy stainless steel ball bearin=
gs ~3/16", which do not corrode. For a flat, you can use a tungsten carbide=20=
tool insert bit for a lathe. You can get flat triangular bits=20=
with about 0.3" sides, quite cheaply. If you epoxy the bearing into a V hole=
made with centre drill on the vertical support, turn the end of the boom ro=
d flat and epoxy the tool bit onto this end, it should work very well. If yo=
u mount the ball in the end of the swing arm, you will have to do a major le=
velling operation every time you dismount the arm.....
This is the damping
https://home.com=
cast.net/~bryangoss/damping.jpg
You shouldn't need oil AND magnetic damping! The magnet set-up you have should give both verti=
cal and horizontal damping! I suggest that you remove the oil and th=
en reduce the magnet separation till you get just sub-critical damping? If y=
ou can't get enough damping, use a 1/8" thick Cu plate. If you slowly deflec=
t the arm 1/2" to one side and then release it, it should just go through ze=
ro by 1/16" or less and then fall back to zero.
There are several problems with oil dam=
ping. It is very temperature sensitive, relatively difficult to set up, it i=
s messy due to oil creep and it collects bugs - giving 'bug-quakes'! It is a=
lso 'non linear' in that it selectively damps short period motion much more=20=
than long period motion. The professionals stopped using it over 50 years ag=
o....
I use a quad NdFeB bar magnet damping s=
et-up. Two 1/4" thick mild steel plates 3.5" long by 2" wide are held apart=20=
by four 1/4" mild steel bolts and additional nuts at each corner. A NS pair=20=
of rectangular NdFeB magnets, 1" x 1/2" x 1/4" are placed on the centre of t=
he face of one plate with the long axis parallel to the 2". A pair of SN mag=
nets are placed on the opposing face of the other plate and the separation i=
s adjusted to about 1/8" to 3/16". The central field gradient is simply huge=
.. A 1/16" or 1/8" thick plate of soft Al or Cu about 2" wide and 3" long is=20=
mounted on the arm. It is important to make the damping plate wider than the=
1" of the magnets to avoid field edge effects. The main damping is over the=
central 1" NS magnet joint. If you mount a L shaped Cu blade horizontally,=20=
you can just slide the magnet array further over it to increase the damping.=
You also reduce the damping by increasing the central magnetic gap. The str=
ay field is low with this design. I put gaffer tape on the magnet faces and=20=
then peel it off before I assemble the two plates, to remove any magnetic de=
bris / whiskers. You always get some and it is very difficult to see...
The bolt and 25mm wire
https://home.comcast.net/~bryangoss/boltwire.jpg
The 5lb weight and coil
https://home.comcas=
t.net/~bryangoss/coil.jpg
If you mount the sensor magnet on the=20=
arm, it will respond to changing magnetic fields, the earth's field, power l=
ine surges, fridge motors, even to passing cars and lorries. If you mount th=
e coil on the arm, it will be ~free of these interfering signals. You may de=
tect movements of a few millionth's of an inch!
The effective length of the arm is a bi=
t shorter than the distance between the centre of the mass and the knife edg=
e. You want this to be ~30 to 40" to give a long period. You might mount the=
mass quite a bit further along the arm?
It is usual to attach the top suspensio=
n wire to a ~3" high vertical extension plate above the screw arm. This give=
s a small vertical pendulum effect and prevents the arm from rotating when i=
t senses movement. This is necessary if you use a ball or wire suspension.
The overall I put the Seismogr=
aph in a clear box to prevent draft bit I need to seal off the bottom this p=
icture shows entire system and my messy shop!!!!!
https://h=
ome.comcast.net/~bryangoss/overall.jpg
This looks OK, but you probably need t=
o seal the edges of the case. You can buy 3" wide clear sticky tape for seal=
ing greenhouse windows. This will take sunlight and it does not loose adhesi=
on with time. Don't use cellotape, or ordinary pvc tape - they won't last lo=
ng and you only want to do the job once!
I would use two longitudinal L angles to support the whol=
e base suspension, the sensor and the damping array plates. I use a single b=
olt at the centre of the mass end of the rig to alter the tilt angle. Thi=
s makes adjustments a whole lot easier. You can set up each section / cl=
earance in turn and the adjustments don't interact much.
https://home.comcast.net/~bryangoss/setup.=
jpg
I would mount the computer and monitor further away from the s=
eismometer. You will certainly see a signal when you turn the monitor on, du=
e to the large magnetic pulse used to demagnetise the screen.
Chris I am not sure how to do t=
he FFT. I hope the screenshot of winsdr will help, Thanks for the help If yo=
u all see something to improve I will try to do it.
Thanks Very Much Bryan S Goss Corinth MS
If you are using WinQuake, there is a t=
ab labelled FFT on the top tool bar. You place the cursor where you want to=20=
start on the trace and click on. There should be a help file if you look for=
it.
Hope that this is of some help! Are the=
re two Corinths in MS?
Regards,
Chris Chapman
Subject: Re: noise
From: BOB BARNS royb1@...........
Date: Mon, 04 Apr 2005 09:48:02 -0400
You can perhaps eliminate convection in your box by attaching a
heater to the underside of the lid. This should stagnate the air since
the air is hotter at the top. I use an ordinary resistor supplied by a
fairly large wall-wart. The resistor dissapates about 10W. A small
lamp would also work.
My box is 2" thick styrafoam which has excellant insulating
properties. If your box is less insulating, it may take more heater power.
I probed the inside of my box with a thermistor and found 2-3 deg. F
difference with the top being hotter.
Bob Barns
1goss@........... wrote:
> I am having problems with noise during the night. Oddly it starts about 9:00pm and ends about 11:00 am.
>
> 9:00pm WinSDR screenshot https://home.comcast.net/~bryangoss/noise9pm.jpg
>
> 11:00am WinSDR screenshot https://home.comcast.net/~bryangoss/noise11am.jpg
>
> I think these pictures will explain much more than I can.
>
> I thought it could be because the shop has a concrete floor and the air in the shop heats up to aournd 70F during the day and cools to around 36F at night. I believe the slower cooling of the floor during the night could be causing convection in the box. I tried to seal the box off and covered it with a blanket but that did not work. Could it be caused by the temperature change in the mineral oil and the vertical dampener?
>
> I ran FFT but to be honest, I'm not sure how to read it.
>
> Thank you for any help you can offer.
>
> Bryan S. Goss
>
>
>
>
>
> __________ NOD32 1.1044 (20050402) Information __________
>
> This message was checked by NOD32 antivirus system.
> http://www.nod32.com
>
>
>
> ------------------------------------------------------------------------
>
> Subject:
> Re: Got it going I think
> From:
> ChrisAtUpw@.......
> Date:
> Sun, 3 Apr 2005 00:37:47 +0000
> To:
> psn-l@..............
>
>
> In a message dated 02/04/2005, 1goss@........... writes:
>
>> I got my Lehman Seismometer up and running I think I may have my gain
>> set a bit high, But I think it is ok.
>
>
>
> HI Bryan,
>
> It looks like you have a fairly high gain on the amplifier. I
> suggest that you examine sections of the trace, do a FFT on it and check
> to see if the ~six second ocean background is dominant or if there is a
> lot of other noise. Try wedging the mass so that it can't move to check
> on instrument noise? I can't tell much from the drumplot, since I don't
> know how it was scaled. It doesn't show any waveforms or any peak
> counts. You need to click on X-Scale at the top of the display and then
> select 'counts'.
> The display shows small deflections during the night, but much
> larger ones during the 'working day'. Do you have a lot of traffic /
> industrial noise?
>
> What sort of suspensions / bearings are you using? A 12 sec plot
> doesn't give you much 'headroom' over the 6 sec microseisms.
>
> Regards,
>
> Chris Chapman
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: RE: noise
From: Jack Ivey ivey@..........
Date: Mon, 4 Apr 2005 12:43:49 -0400
Bryan,
It might also help to add insulation to the bottom of the box. Of course
you have to have holes to let the seismo feet touch the floor
underneath, and it would have to be thin enough that there is
no contact between the seismo and the insulation.
Jack
-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@............... On
Behalf Of BOB BARNS
Sent: Monday, April 04, 2005 9:48 AM
To: psn-l@..............
Subject: Re: noise
You can perhaps eliminate convection in your box by attaching a
heater to the underside of the lid. This should stagnate the air since
the air is hotter at the top. I use an ordinary resistor supplied by a
fairly large wall-wart. The resistor dissapates about 10W. A small
lamp would also work.
My box is 2" thick styrafoam which has excellant insulating
properties. If your box is less insulating, it may take more heater power.
I probed the inside of my box with a thermistor and found 2-3 deg. F
difference with the top being hotter.
Bob Barns
1goss@........... wrote:
> I am having problems with noise during the night. Oddly it starts about
9:00pm and ends about 11:00 am.
>
> 9:00pm WinSDR screenshot https://home.comcast.net/~bryangoss/noise9pm.jpg
>
> 11:00am WinSDR screenshot
https://home.comcast.net/~bryangoss/noise11am.jpg
>
> I think these pictures will explain much more than I can.
>
> I thought it could be because the shop has a concrete floor and the air in
the shop heats up to aournd 70F during the day and cools to around 36F at
night. I believe the slower cooling of the floor during the night could be
causing convection in the box. I tried to seal the box off and covered it
with a blanket but that did not work. Could it be caused by the temperature
change in the mineral oil and the vertical dampener?
>
> I ran FFT but to be honest, I'm not sure how to read it.
>
> Thank you for any help you can offer.
>
> Bryan S. Goss
>
>
>
>
>
> __________ NOD32 1.1044 (20050402) Information __________
>
> This message was checked by NOD32 antivirus system.
> http://www.nod32.com
>
>
>
> ------------------------------------------------------------------------
>
> Subject:
> Re: Got it going I think
> From:
> ChrisAtUpw@.......
> Date:
> Sun, 3 Apr 2005 00:37:47 +0000
> To:
> psn-l@..............
>
>
> In a message dated 02/04/2005, 1goss@........... writes:
>
>> I got my Lehman Seismometer up and running I think I may have my gain
>> set a bit high, But I think it is ok.
>
>
>
> HI Bryan,
>
> It looks like you have a fairly high gain on the amplifier. I
> suggest that you examine sections of the trace, do a FFT on it and check
> to see if the ~six second ocean background is dominant or if there is a
> lot of other noise. Try wedging the mass so that it can't move to check
> on instrument noise? I can't tell much from the drumplot, since I don't
> know how it was scaled. It doesn't show any waveforms or any peak
> counts. You need to click on X-Scale at the top of the display and then
> select 'counts'.
> The display shows small deflections during the night, but much
> larger ones during the 'working day'. Do you have a lot of traffic /
> industrial noise?
>
> What sort of suspensions / bearings are you using? A 12 sec plot
> doesn't give you much 'headroom' over the 6 sec microseisms.
>
> Regards,
>
> Chris Chapman
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: WWSN Drum Recorder
From: Richard Webb dwebb002@.............
Date: Mon, 04 Apr 2005 16:20:46 -0400
Hi,
I have a 3 sheet drum recorder from the old WWSN system. It was set up
to record photographically. Once upon a time I had plans to convert it
to a standard pen recorder by ran into $$ problem. I also still have
some of the components for the photo system of the recorder. I do not
have the galvanometer component.
I am looking for a good home for it if anyone is interested in an
excellent drum recorder in excellent condition. Unfortunately, it
weighs 50-100 lbs so shipping is not a good idea. However, I will be
driving to the SSA meeting in a few weeks and would be willing to bring
it with me and give it (no charge) to anyone who wants it. I also have
a few pen parts and a box of paper. I just want to find it a good home
and not throw it in the trash.
Let me know if you are interested.
Thanks,
Dick Webb
Raleigh, NC
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: improvements
From: ChrisAtUpw@.......
Date: Mon, 4 Apr 2005 18:44:59 EDT
In a message dated 04/04/2005, 1goss@........... writes:
> I would like very much to see detailed pictures of your setup. It would
> help me to better understand the improvements you suggested.
HI Bryan,
I am away from home at the moment, but I will do a sketch. I use a
very different design. My concern when looking at your setup is to try to think
what you can do to get your system to work well.
> I have 2 questions:
> 1. If you put the coil on the boom how do you keep the wire from interfering
> with the swing or period.
You run ordinary two core wire along the arm, taping it on every 6".
Over the bearing you mount two vertical 'hairpin' shapes of the thinnest magnet
wire that you can easily get, maybe 3" long. These are soldered between the
cable on the arm and the cable from the baseplate to the amplifier. The amount
of spring in them is tiny and should be ~constant. You can also wind ~10 turn
coils onto a 3/16" rod and loop the free coil over the bearing.
RS sell 30G magnet wire and 30 gauge wrap wire. This is 10 thou dia,
which is still a bit thick. I can get 5 thou wire wrap easily from other
sources, but I use a reel of 2 thou which I bought many years ago. If you can get
wire with polyurethane insulation, you can solder it directly using a hot iron.
The insulation just melts.
> 2 I used 3/8 all thread, as you could see. I was afraid it would bend under
> the weight as I noted the 4ft length of the rod was flexible when I bought
> it.
> What size rod did you use? What size should I use? oops went over 2
> questions.
You should be able to get about 30" OK? What is the ~distance between
the centre of the weight and the knife edge at the moment?
I don't use 'all-thread' at all. I use 1/2" nominal stainless steel
water pipe (~19/32") and brass compression water fittings, stop ends, Ts and Xs.
I drill out the central hole of the T or X to give a clearance for the pipe.
> 3 My nightmare the only place I can put the seismograph is in my shop it is
> very UN-level. I could not believe how much. It sets on sand near a ditch
> when I level the boom their is over an inch difference from one end to the
> other, this makes a hard job harder.
> I had considered pouring a small amount of concrete to try and fix this.
Ordinary concrete with gravel in it can be quite 'noisy' as the
temperature changes, although 3' x 2' paving slabs have been used. The recommended
mix is 50:50 cement and sand by volume. You mix it fairly wet and vibrate it if
possible, to remove air bubbles. You cover it with polythene sheet for over a
week to keep it wet and allow it to 'cure'. It may take a month to cure
fully.
What is your floor made of? It looks like wood block....
What is the construction of your 'shop'?
What is the ground material if you dig a hole outside? Do you get to
solid rock at any practicable depth?
> also tonight late I had very little noise so it seems as their was no big
> temperature contrast, this may well be the bigger problem. I ran FFT on the
> low noise output of the seismograph and I clearly saw a spike the 6 sec
> microseisms.
You need to be able to see the 6 sec microseism peak quite clearly.
This is a good thing I right? but I am still going to improve it.
I can't see a 6 sec peak (0.17 Hz) on the FFT you posted. You read the
frequency / period figures at the top of the screen for the ^ cursor
position. It is the larger amplitude low frequency stuff between 0.1 and 0.01 Hz which
concerns me. It is maybe 100x what it should be. I suspect that the noise is
at least partially due to air currents, from your description.
Could it be partially due to your whole shop heating and cooling? Does
it make any creaking noises? How does wind effect the signal?
Regards,
Chris Chapman
In a message dated 04/04/2005, 1gos=
s@........... writes:
I would like very much to see d=
etailed pictures of your setup. It would help me to better understand the im=
provements you suggested.
HI Bryan,
I am away from home at the moment, but=20=
I will do a sketch. I use a very different design. My concern when looking a=
t your setup is to try to think what you can do to get your system to=
work well.
I have 2 questions:
1. If you put the coil on the boom how do you keep the wire from interfering=
with the swing or period.
You run ordinary two core wire along t=
he arm, taping it on every 6". Over the bearing you mount two vertical 'hair=
pin' shapes of the thinnest magnet wire that you can easily get, maybe 3" lo=
ng. These are soldered between the cable on the arm and the cable from the b=
aseplate to the amplifier. The amount of spring in them is tiny and should b=
e ~constant. You can also wind ~10 turn coils onto a 3/16" rod and loop the=20=
free coil over the bearing.
RS sell 30G magnet wire and 30 gauge wr=
ap wire. This is 10 thou dia, which is still a bit thick. I can get 5 thou w=
ire wrap easily from other sources, but I use a reel of 2 thou which I bough=
t many years ago. If you can get wire with polyurethane insulation, you can=20=
solder it directly using a hot iron. The insulation just melts.
2 I used 3/8 all thread, as you=
could see. I was afraid it would bend under the weight as I noted the 4ft l=
ength of the rod was flexible when I bought it.
What size rod did you use? What size should I use? oops went over 2 question=
s.
You should be able to get about 30" OK=
? What is the ~distance between the centre of the weight and the knife edge=20=
at the moment?
I don't use 'all-thread' at all. I use 1/2" n=
ominal stainless steel water pipe (~19/32") and brass compression water fitt=
ings, stop ends, Ts and Xs. I drill out the central hole of the T or X to gi=
ve a clearance for the pipe.
3 My nightmare the only place I=
can put the seismograph is in my shop it is very UN-level. I could not beli=
eve how much. It sets on sand near a ditch when I level the boom their=
is over an inch difference from one end to the other, this makes a hard job=
harder.
I had considered pouring a small amount of concrete to try and fix this.
Ordinary concrete with gravel in it ca=
n be quite 'noisy' as the temperature changes, although 3' x 2' paving slabs=
have been used. The recommended mix is 50:50 cement and sand by volume. You=
mix it fairly wet and vibrate it if possible, to remove air bubbles. You co=
ver it with polythene sheet for over a week to keep it wet and allow it to '=
cure'. It may take a month to cure fully.
What is your floor made of? It looks li=
ke wood block....
What is the construction of your 'shop'=
?
What is the ground material if you dig=20=
a hole outside? Do you get to solid rock at any practicable depth?
also tonight late I had very li=
ttle noise so it seems as their was no big temperature contrast, this may we=
ll be the bigger problem. I ran FFT on the low noise output of the seismogra=
ph and I clearly saw a spike the 6 sec microseisms.
You need to be able to see the 6 sec m=
icroseism peak quite clearly.
This is a good thing I right? but I am still going to improve it.
I can't see a 6 sec peak (0.17 Hz) on t=
he FFT you posted. You read the frequency / period figures at the top of the=
screen for the ^ cursor position. It is the larger amplitude low frequency=20=
stuff between 0.1 and 0.01 Hz which concerns me. It is maybe 100x what it sh=
ould be. I suspect that the noise is at least partially due to air currents,=
from your description.
Could it be partially due to your whole=
shop heating and cooling? Does it make any creaking noises? How does wind e=
ffect the signal?
Regards,
Chris Chapman
Subject: Re: improvements
From: 1goss@...........
Date: Tue, 05 Apr 2005 09:33:31 +0000
Chris,
"What is the ~distance between the center of the weight and the knife edge at the moment?"
About 15 inches.
"What is your floor made of?"
My shop floor is cement 20x40.
"What is the construction of your 'shop'?"
Wood 2 level barn style.
"What is the ground material if you dig a hole outside?"
Red clay
"Do you get to solid rock at any practicable depth?"
No solid rock here, to 70 ft +.
"How does wind effect the signal?"
Wind to 5 MPH does not affect the output. I am not sure about more than that.
"Does it make any creaking noises?"
Yes but mostly with sharp temperature changes.
Could you send me a psn file with nominal noise and 6 sec microseisms, or if someone would like to post a link to a file. I would like to see about a Minute of time from a good signal.
The noise has greatly decreased. Here is a link to the latest FFT with the lower noise level.
I am not sure bout the 6 sec microseisms. This is 1 Minute of time.
WinQuake 1 Min https://home.comcast.net/~bryangoss/WinQuake.jpg
FFT 1 Min https://home.comcast.net/~bryangoss/FFT.jpg
Thanks for all the help
Bryan S Goss
In a message dated 04/04/2005, 1goss@........... writes:
> I would like very much to see detailed pictures of your setup. It would
> help me to better understand the improvements you suggested.
HI Bryan,
I am away from home at the moment, but I will do a sketch. I use a
very different design. My concern when looking at your setup is to try to think
what you can do to get your system to work well.
> I have 2 questions:
> 1. If you put the coil on the boom how do you keep the wire from interfering
> with the swing or period.
You run ordinary two core wire along the arm, taping it on every 6".
Over the bearing you mount two vertical 'hairpin' shapes of the thinnest magnet
wire that you can easily get, maybe 3" long. These are soldered between the
cable on the arm and the cable from the baseplate to the amplifier. The amount
of spring in them is tiny and should be ~constant. You can also wind ~10 turn
coils onto a 3/16" rod and loop the free coil over the bearing.
RS sell 30G magnet wire and 30 gauge wrap wire. This is 10 thou dia,
which is still a bit thick. I can get 5 thou wire wrap easily from other
sources, but I use a reel of 2 thou which I bought many years ago. If you can get
wire with polyurethane insulation, you can solder it directly using a hot iron.
The insulation just melts.
> 2 I used 3/8 all thread, as you could see. I was afraid it would bend under
> the weight as I noted the 4ft length of the rod was flexible when I bought
> it.
> What size rod did you use? What size should I use? oops went over 2
> questions.
You should be able to get about 30" OK? What is the ~distance between
the centre of the weight and the knife edge at the moment?
I don't use 'all-thread' at all. I use 1/2" nominal stainless steel
water pipe (~19/32") and brass compression water fittings, stop ends, Ts and Xs.
I drill out the central hole of the T or X to give a clearance for the pipe.
> 3 My nightmare the only place I can put the seismograph is in my shop it is
> very UN-level. I could not believe how much. It sets on sand near a ditch
> when I level the boom their is over an inch difference from one end to the
> other, this makes a hard job harder.
> I had considered pouring a small amount of concrete to try and fix this.
Ordinary concrete with gravel in it can be quite 'noisy' as the
temperature changes, although 3' x 2' paving slabs have been used. The recommended
mix is 50:50 cement and sand by volume. You mix it fairly wet and vibrate it if
possible, to remove air bubbles. You cover it with polythene sheet for over a
week to keep it wet and allow it to 'cure'. It may take a month to cure
fully.
What is your floor made of? It looks like wood block....
What is the construction of your 'shop'?
What is the ground material if you dig a hole outside? Do you get to
solid rock at any practicable depth?
> also tonight late I had very little noise so it seems as their was no big
> temperature contrast, this may well be the bigger problem. I ran FFT on the
> low noise output of the seismograph and I clearly saw a spike the 6 sec
> microseisms.
You need to be able to see the 6 sec microseism peak quite clearly.
This is a good thing I right? but I am still going to improve it.
I can't see a 6 sec peak (0.17 Hz) on the FFT you posted. You read the
frequency / period figures at the top of the screen for the ^ cursor
position. It is the larger amplitude low frequency stuff between 0.1 and 0.01 Hz which
concerns me. It is maybe 100x what it should be. I suspect that the noise is
at least partially due to air currents, from your description.
Could it be partially due to your whole shop heating and cooling? Does
it make any creaking noises? How does wind effect the signal?
Regards,
Chris Chapman
In a message dated 04/04/2005, 1gos=
s@........... writes:
I would like very much to see d=
etailed pictures of your setup. It would help me to better understand the im=
provements you suggested.
HI Bryan,
I am away from home at the moment, but=20=
I will do a sketch. I use a very different design. My concern when looking a=
t your setup is to try to think what you can do to get your system to=
work well.
I have 2 questions:
1. If you put the coil on the boom how do you keep the wire from interfering=
with the swing or period.
You run ordinary two core wire along t=
he arm, taping it on every 6". Over the bearing you mount two vertical 'hair=
pin' shapes of the thinnest magnet wire that you can easily get, maybe 3" lo=
ng. These are soldered between the cable on the arm and the cable from the b=
aseplate to the amplifier. The amount of spring in them is tiny and should b=
e ~constant. You can also wind ~10 turn coils onto a 3/16" rod and loop the=20=
free coil over the bearing.
RS sell 30G magnet wire and 30 gauge wr=
ap wire. This is 10 thou dia, which is still a bit thick. I can get 5 thou w=
ire wrap easily from other sources, but I use a reel of 2 thou which I bough=
t many years ago. If you can get wire with polyurethane insulation, you can=20=
solder it directly using a hot iron. The insulation just melts.
2 I used 3/8 all thread, as you=
could see. I was afraid it would bend under the weight as I noted the 4ft l=
ength of the rod was flexible when I bought it.
What size rod did you use? What size should I use? oops went over 2 question=
s.
You should be able to get about 30" OK=
? What is the ~distance between the centre of the weight and the knife edge=20=
at the moment?
I don't use 'all-thread' at all. I use 1/2" n=
ominal stainless steel water pipe (~19/32") and brass compression water fitt=
ings, stop ends, Ts and Xs. I drill out the central hole of the T or X to gi=
ve a clearance for the pipe.
3 My nightmare the only place I=
can put the seismograph is in my shop it is very UN-level. I could not beli=
eve how much. It sets on sand near a ditch when I level the boom their=
is over an inch difference from one end to the other, this makes a hard job=
harder.
I had considered pouring a small amount of concrete to try and fix this.
Ordinary concrete with gravel in it ca=
n be quite 'noisy' as the temperature changes, although 3' x 2' paving slabs=
have been used. The recommended mix is 50:50 cement and sand by volume. You=
mix it fairly wet and vibrate it if possible, to remove air bubbles. You co=
ver it with polythene sheet for over a week to keep it wet and allow it to '=
cure'. It may take a month to cure fully.
What is your floor made of? It looks li=
ke wood block....
What is the construction of your 'shop'=
?
What is the ground material if you dig=20=
a hole outside? Do you get to solid rock at any practicable depth?
also tonight late I had very li=
ttle noise so it seems as their was no big temperature contrast, this may we=
ll be the bigger problem. I ran FFT on the low noise output of the seismogra=
ph and I clearly saw a spike the 6 sec microseisms.
You need to be able to see the 6 sec m=
icroseism peak quite clearly.
This is a good thing I right? but I am still going to improve it.
I can't see a 6 sec peak (0.17 Hz) on t=
he FFT you posted. You read the frequency / period figures at the top of the=
screen for the ^ cursor position. It is the larger amplitude low frequency=20=
stuff between 0.1 and 0.01 Hz which concerns me. It is maybe 100x what it sh=
ould be. I suspect that the noise is at least partially due to air currents,=
from your description.
Could it be partially due to your whole=
shop heating and cooling? Does it make any creaking noises? How does wind e=
ffect the signal?
Regards,
Chris Chapman
Subject: Question About Analog Seismo Telemetered On 163.797 in So.Cal
From: Douglas Gavilanes gavilan1@.............
Date: Wed, 06 Apr 2005 15:35:00 -0700
Greetings from under my rock. I have received a few questions recently
from fellow amateur radio folks about the *general* location of the
seismo that is currently telemetered via VHF (163.797MHz) into the LA
basin (for the Caltech Seismo Lab). I'm not seeking an exact location.
Most believe it to be located at Crystal Lake, L.A. Co., but I believe
having heard that it was on Catalina Island. The Crystal Lake seismo
(which most of us affiliated with PSN Pasadena listened to) was just off
of 162.810, but it went fiber or satellite ages ago. Many of us built
discriminators back then for its 680Hz tone, with data outputs, alarms,
etc. In any case, a few ham folks would like to know which way to point
a dedicated beam antenna for best signal reception. Since it is so
weak, one can't be sure if their antenna is aimed at the transmitter, or
at a reflection off of a mountain or building. Any direction here (pun
intended) is appreciated. Off list is OK, if you're concerned.
Regards,
Doug Gavilanes
Garden Grove, CA.
n6xqy@........
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: Question About Analog Seismo Telemetered On 163.797 in So.Cal
From: Larry Cochrane lcochrane@..............
Date: Thu, 07 Apr 2005 19:50:21 -0700
Doug,
I have located remote sensor locations by recording the data and using known local
event epicenters to triangulate the locate of the sensor. You can use my WinQuake
program to do this. Another way is to use the P arrival time and look at an event
list that has P arrive times for each station. If you have accurate timing you should
be able to find the station. The local USGS or maybe Cal Tech should publish a list
with this information in it. Once you have the station ID you should be able to look
up the sensor location on the USGS site.
Good luck.
Larry Cochrane
Redwood City, PSN
Douglas Gavilanes wrote:
> Greetings from under my rock. I have received a few questions recently
> from fellow amateur radio folks about the *general* location of the
> seismo that is currently telemetered via VHF (163.797MHz) into the LA
> basin (for the Caltech Seismo Lab). I'm not seeking an exact location.
> Most believe it to be located at Crystal Lake, L.A. Co., but I believe
> having heard that it was on Catalina Island. The Crystal Lake seismo
> (which most of us affiliated with PSN Pasadena listened to) was just off
> of 162.810, but it went fiber or satellite ages ago. Many of us built
> discriminators back then for its 680Hz tone, with data outputs, alarms,
> etc. In any case, a few ham folks would like to know which way to point
> a dedicated beam antenna for best signal reception. Since it is so
> weak, one can't be sure if their antenna is aimed at the transmitter, or
> at a reflection off of a mountain or building. Any direction here (pun
> intended) is appreciated. Off list is OK, if you're concerned.
>
> Regards,
>
> Doug Gavilanes
> Garden Grove, CA.
> n6xqy@........
>
>
> __________________________________________________________
>
> Public Seismic Network Mailing List (PSN-L)
>
> To leave this list email PSN-L-REQUEST@.............. with
> the body of the message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.
>
>
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: first event
From: 1goss@...........
Date: Fri, 08 Apr 2005 07:24:08 +0000
I sent this to Center for Earthquake Research and Information (CERI)
And to my surprise got this response this was interesting + it is the first event I recorded on my Lehman seismometer.
My letter to CERI :
> >I see an event that looks like a micro quake
> >on the Recent Helicorder Display
> >"http://folkworm.ceri.memphis.edu/heli_nm/"
> > PWLA EHZ NM : Pickwick Lake, AL
> > I saw it on my homebuilt Lehman seismometer
> >In corinth MS. as well this is why I ask.
> >
> >Event UTC 4/5/05 21:07:30 to 21:08:51
> >This is my data
> >https://home.comcast.net/~bryangoss/micro.jpg
> >
> >It is not on the Recent Earthquakes in Central US that I can find??
THE REPLY BY CERI:
On Thu, 7 Apr 2005, Gary Patterson wrote:
> Hello Bryan,
>
> Thanks for your input. Seems we may have a processing glitch for
> that event (maybe from the time change...maybe from something else).
> We listed an event at
> 2.9 2005/04/05 15:37:43 36.150N 83.690W 10.1 (20:37:43 (UTC) ....
> looks like it should have been listed at the time you specified
> (about 21:07 for the first arrival at pickwick). It is very clear on
> the pickwick (PWLA) station.
>
> I know that these types of glitches dont happen often and I
> appreciate you bringing it to our attention. Staff are looking for
> the problem now.
>
> Additionally, your Lehman seismometer seems to be working well.
> Hopefully you will continue to monitor earthquakes in the
> area.....it's great to have someone else out there.
>
> Regards,
>
> Good luck
This message was sent to you by 69.244.24.49
> >on Wed Apr 6 07:15:29 2005 (GMT).
>
Mitch
Center for Earthquake Research and Information (CERI)
University of Memphis Ph: 901-678-4940
Memphis, TN 38152 Fax: 901-678-4734
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Telemetry
From: 1goss@...........
Date: Sat, 09 Apr 2005 10:10:05 +0000
I have a few questons about Telemetry. I am about 30 miles from a station at PWLA EHZ NM : Pickwick Lake, AL and wanted to know If I could pick up the Telemetry from that station.If it has Telemetry and what frequency it would be on. This statement was on CERI pape.
"The CERI seismic networks are subdivided into autonomous, remote processing nodes. Each node acts as a central site for FM telemetry reception and processing, digitizing, and earthworm processing. Digital connections to Memphis are established by various means. Some stations are additionally telemetered back to Memphis."
I would like to try Larry Cochrane,s Telemetry Demodulator Board.
Thanks Bryan Goss
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: Telemetry
From: Richard Webb dwebb002@.............
Date: Sat, 09 Apr 2005 08:05:42 -0400
You might give the people at CERI a call or email. They are an
extremely helpful bunch.
Dick
1goss@........... wrote:
>I have a few questons about Telemetry. I am about 30 miles from a station at PWLA EHZ NM : Pickwick Lake, AL and wanted to know If I could pick up the Telemetry from that station.If it has Telemetry and what frequency it would be on. This statement was on CERI pape.
> "The CERI seismic networks are subdivided into autonomous, remote processing nodes. Each node acts as a central site for FM telemetry reception and processing, digitizing, and earthworm processing. Digital connections to Memphis are established by various means. Some stations are additionally telemetered back to Memphis."
>
>I would like to try Larry Cochrane,s Telemetry Demodulator Board.
>Thanks Bryan Goss
>__________________________________________________________
>
>Public Seismic Network Mailing List (PSN-L)
>
>To leave this list email PSN-L-REQUEST@.............. with
>the body of the message (first line only): unsubscribe
>See http://www.seismicnet.com/maillist.html for more information.
>
>
>
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: first event
From: "Thomas Dick" dickthomas01@.............
Date: Sat, 9 Apr 2005 07:47:26 -0500
I, too, copied that event here in Evansville,IN ... arrived at 21:09
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Network time standard
From: "Steve Hammond" shammon1@.............
Date: Sat, 9 Apr 2005 09:00:18 -0700
PSN members,
I'm writing to report on a software network time client server software
program that is compatible with WinSDR. I'm using Larry's serial connected
A/D hardware with a Motorola GPS for data collection and realized that I
could have my own home network time standard if I could find a compatible
software package.
After looking and trying three different products, I selected Net Time
version 2.1 because it works seamlessly with WinSDR. You can obtain a trial
version of the software from Http://www.han-soft.com I think you will find
it to be compatible with all the MS operating systems.
A few observation notes: While you can install the same copy of the trial
software on two different systems, you need to purchase a server "Full
License" for $25.00 for the time server (the machine running WinSDR) and a
"Client License" for $12.99 for each client using the new network time
service. The software includes a list of known Internet time servers and
also allows you to assign the local IP address of your in-house network time
server. The software is configurable with and support several different
protocols. I'm using SNTP on port 123 which does not conflict with any other
ports currently in use by the system. I had some issues with the initial
install because I didn't understand the licensing methodology but was able
to sort it out with the help of the Han-soft support rep who provide prompt
and high-quality service.
If you don't have a GPS, as I said, the software comes with an extensive
list of network time servers that can be accessed via the Internet to obtain
accurate time. Overall, the experience with this software package has been
very positive and after 30-days of testing I'm now recommending it to other
members of the Public Seismic Network.
Regards, Steve Hammond, Aptos CA
Public Seismic Network San Jose California
Http://www.publicseismicnetowrk.com
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: Network time standard
From: ian ian@...........
Date: Sat, 09 Apr 2005 17:18:11 +0100
an interesting experiment would be to see what the magnitude of the time
drift is between a computer using an internet network time server
(synchronised at regular intervals) and one using a gps time board.
It would also be interesting to then calculate what the typical
positional error would be (of an epicentre) for a pc using an internet
network time server, using gps time as a base line.
Ian Smith
Steve Hammond wrote:
>PSN members,
>I'm writing to report on a software network time client server software
>program that is compatible with WinSDR. I'm using Larry's serial connected
>A/D hardware with a Motorola GPS for data collection and realized that I
>could have my own home network time standard if I could find a compatible
>software package.
>
>After looking and trying three different products, I selected Net Time
>version 2.1 because it works seamlessly with WinSDR. You can obtain a trial
>version of the software from Http://www.han-soft.com I think you will find
>it to be compatible with all the MS operating systems.
>
>A few observation notes: While you can install the same copy of the trial
>software on two different systems, you need to purchase a server "Full
>License" for $25.00 for the time server (the machine running WinSDR) and a
>"Client License" for $12.99 for each client using the new network time
>service. The software includes a list of known Internet time servers and
>also allows you to assign the local IP address of your in-house network time
>server. The software is configurable with and support several different
>protocols. I'm using SNTP on port 123 which does not conflict with any other
>ports currently in use by the system. I had some issues with the initial
>install because I didn't understand the licensing methodology but was able
>to sort it out with the help of the Han-soft support rep who provide prompt
>and high-quality service.
>
>If you don't have a GPS, as I said, the software comes with an extensive
>list of network time servers that can be accessed via the Internet to obtain
>accurate time. Overall, the experience with this software package has been
>very positive and after 30-days of testing I'm now recommending it to other
>members of the Public Seismic Network.
>
>
>Regards, Steve Hammond, Aptos CA
>Public Seismic Network San Jose California
>Http://www.publicseismicnetowrk.com
>
>__________________________________________________________
>
>Public Seismic Network Mailing List (PSN-L)
>
>To leave this list email PSN-L-REQUEST@.............. with
>the body of the message (first line only): unsubscribe
>See http://www.seismicnet.com/maillist.html for more information.
>
>
>
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: Network time standard
From: ChrisAtUpw@.......
Date: Sat, 9 Apr 2005 16:05:42 EDT
In a message dated 09/04/2005, shammon1@............. writes:
If you don't have a GPS, as I said, the software comes with an extensive
list of network time servers that can be accessed via the Internet to obtain
accurate time. Overall, the experience with this software package has been
very positive and after 30-days of testing I'm now recommending it to other
members of the Public Seismic Network.
Hi Steve,
Does it give any timing accuracies in milli seconds for the various time
servers?
One of the problems with time services is that while the signal may
leave the server on time, it may be digitally delayed on it's way though the
telecom system. Since there are many services now operating, the inaccuracy
around some timing marks may be very significant.
What timing errors have you measured, please?
About the Public NTP Time Server Lists
The lists are provided for information purposes only and represent the best
information available at the current date. The operators of the servers listed
do not commit to provide time service other than on a volunteer basis and
with no guarantee of accuracy or availability. Further information of a
technical nature can be obtained from the _www.ntp.org_ (http://www.ntp.org/) site,
the _comp.protocols.time.ntp_ (news:comp.protocols.time.ntp) newsgroup, or
the _NTP Support_ (http://ntp.isc.org/bin/view/Support/WebHome) Web.
Regards,
Chris Chapman
In a message dated 09/04/2005, shammon1@............. writes:
<=
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=
Hi Steve,
Does it give any timing accuracies in mill=
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